$a = [ [ 0..2 ], [0..10],[0..100] ];
my ($min, $max,$sum) = (undef, 0, 0);
for (@$a){
  $sum += my $a_length = @$_;
  $min = $a_length if $a_length < $min or not defined $min;
  $max = $a_length if $a_length > $max;
}
my $avg = $sum/ @$a;
print "Avg: $avg; Min: $min; Max: $max\n";